Molecular Response Method for Solvated Molecules in Nonequilibrium Solvation

We present an extension of the molecular response method of solvated compounds. The extension treats in a proper fashion the effects of nonequilibrium solvation on the molecular properties of the solvated compound. The molecular properties evaluated within the response formalism are properties that are measured using high-frequency electromagnetic fields. We consider the changes in the molecular properties due to nonequilibrium solvation. The nonequilibrium solvation arises from changes in the molecular charge distribution induced by the high-frequency perturbation. The optical polarization vector is at all times assumed to be in equilibrium with the charge distribution of the solute, contrary to the inertial polarization, which is not necessarily in equilibrium with the charge distribution of the solute. We calculate shifts of excitation energies and frequency-dependent polarizabilities as a function of the optical and static dielectric constants.